Micro-electronic power supply for electrochromic eyewear

ABSTRACT

A power and control system for micro-electronics is described, as for lightweight, battery-powered electrochromic (EC) eyewear. Preferably such system includes a primary, lithium-type cell and a secondary, sealed lead acid-type cell in a hybrid, power-sharing configuration capable of supplying the low-energy, high-current (pulse) drain requirements of microelectronics, e.g. a switchable EC lens. A switch-mode power supply controller manages the power-sharing load on the hybrid battery system such that the secondary cell is charged by the primary cell. The system is capable of meeting short-term pulse drain requirements of switching EC lenses from clear to fully darkened at an acceptably fast rate and long-term operating life requirements of approximately 1500 cycles. The invented lead acid-type battery preferably is elongate, of uniform, right-rectangular cross section and provides over 20 mA-hours&#39; capacity and the invented lithium-type battery preferably also is elongate, of uniform, right-rectangular cross section and provides over 180 mA-hours&#39; capacity, all in a tiny volume compatible with one or more volume-restricted spaces. Preferably, the lithium-type and lead acid-type batteries are of approximately equal form factor and volume, for symmetric placement thereof in a void within either temple. The temples are hingedly connected with the eyewear&#39;s front piece via a unique leaf spring that biases the former into one of two orientations relative to the latter. Dual like-cell battery configurations also are disclosed, along with a flexible circuit defining one or more frame-mounted transmissivity switches. A microcontroller is described that fits within a tiny void formed in the eyewear&#39;s bridge. Finally an external, battery-powered battery charger case and circuit are described for use with EC eyewear powered by dual lead acid batteries.

This is a continuation of application Ser. No. 08/637,587 filed Apr. 24,1996 now abandoned which is a continuation of application Ser. No.08/119,749 filed Sep. 10, 1993 now abandoned.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to power and control systems formicro-electronics. More particularly, it concerns a battery, powermanagement and control system therefor that features a high-power,long-life switching mode power supply compatible with various batterychemistries and an associated controller for supplying relativelyshort-term high-current switchable primary and relatively long-termlow-current standby DC power in a volume-restricted space such as thatof electrochromic (EC) eyewear. In a dual lead-acid batteryconfiguration, an external battery charger integral with an EC eyewearcase is provided. The invention also involves a unique temple includinga leaf spring hinge assembly and a protective temple tip coating usefulfor eyewear generally.

Currently available electrochromic (EC) eyewear is characterized by longtransmissivity switching times, short operating (e.g. battery) life anda bulky frame that reduce its aesthetic appeal. The invention representsa broad-based approach to solving various problems with power supply andcontroller microelectronics to achieve greatly improved switching times,longer and more stable operation and consumer demands for more aestheticand lightweight frames. It does so with various battery chemistrieshaving form factors compatible with eyewear temples, withmicro-miniaturized power supply and controller electronics having a formfactor compatible with eyewear bridges, with signal distribution andswitching via flex circuitry, with improved hinges connecting templesand eyewires, with lens-protective temple tip coatings and with anexternal battery charger case for convenient recharging of lead acidcells in one battery configuration.

Hybrid battery systems are not new. U.S. Pat. No. 4,770,954 describes aswitching power supply having two battery types in a hybrid arrangementhaving their positive output terminals connected in parallel throughcommon-cathode connected diodes to supply an output voltagealternatively from either a high-energy density source or a low-energydensity source. The sources are said to be lithium-type and zinc-silveroxide-type. U.S. Pat. No. 4,977,899 describes a dual-battery system foruse in lightweight, portable electrocardiograph (ECG) monitoring devicesalso have been proposed. A lithium battery provides reduced-voltagelevel to sustain a volatile read-and-write memory (RAM) device over thelong life of the monitor while triple, series-connectedreplaceable/rechargeable alkaline batteries provide primary power tocircuit elements for a short term of high-demand ECG data monitoring andrecording. U.S. Pat. No. 4,883,728 describes a lead acid automotivebattery that meets diverse current requirements by providing cellshaving different electrode thicknesses.

It has been determined that use of a primary cell alone cannot best meetcertain pulse power drain demands placed, for example, on commerciallyavailable silver oxide "button" batteries (such as those used in watchesand some pocket cameras) or lithium cells having a small form factor.This is because of high internal resistance in such batteries that leadsto internal losses during pulse discharge, and the danger of damage whensuch batteries are over-driven.

The invention in a first embodiment solves this problem by using dualsilver oxide batteries, in another by using dual lead acid batteries andin yet another by using dual lithium/thionyl chloride batteries. Theinvention in still another embodiment solves this problem by using thelower internal resistance of a lead acid cell secondary battery toprovide the pulse rate requirements, while using a lithium-type cellprimary battery to provide the needed capacity for long life. Theinvention in these various embodiments includes a controller thataccommodates any of the various battery combinations and provides theneeded switching currents and voltages to meet the demanding EC eyewearswitching and lifetime requirements.

Briefly summarizing the merits of the various embodiments, the inventedsystem preferably includes a primary, lithium-type cell and a secondary,sealed lead acid cell in a hybrid, power-sharing configuration capableof supplying the relatively low-energy high-current (pulse) drain andrelatively high-energy, low-current requirements, for example, of aswitchable EC lens, while providing high operating cycle life and shelflife. A switch-mode power supply controller manages the power-sharingload on the hybrid batteries such that the secondary cell is charged bythe primary cell. The system is capable of meeting the demanding ECshort-term lens pulse drain requirements of approximately 60-130milliamps (mA) for five to ten seconds (required to switch EC lensesfrom clear to fully darkened at an acceptably fast rate) and thelong-term life requirements of over two thousand cycles. The inventedlead acid battery provides approximately 12-15 mA-hours' capacity andthe invented lithium-type battery provides nearly 180 mA-hours'capacity, all in a tiny volume of approximately one milliliter (1 ml)that is fittable, for example, within voids formed in either of theframe members of eyeglasses. Preferably, the lithium-type and leadacid-type batteries are of approximately equal form factor and volume,for symmetric placement thereof in such volume-restricted spaces.

In the dual lithium/thionyl chloride battery subsystem, a nominal 3.65volts (3.65 V) output of the dual, parallel-connected lithium-typebatteries (each approximately 35 mm long) is converted down to a maximumpotential of 2.2 V at sufficiently higher current that rapidly switchingthe EC lenses is possible. In the dual lead acid battery subsystem, inwhich the batteries are connected in series, a nominal 4 V output of thebatteries is used by a lens driver circuit to drive the EC lenses at ahigh switching current that characterizes the lead acid cells, and anexternal battery charger case provides for convenient, periodicrecharging of the lead acid cells. In the dual or quad silver oxidebattery subsystem, two to four batteries are operated in series and/orparallel nominally to to supply 4 V at up to approximately -150 mA ≦I+150 mA. Accordingly, the best characteristics of each of the cell typesflexibly are accommodated in various form factors and with variouslifetimes that are compatible with a wide range of EC eyewear andsimilarly demanding applications.

The invented system in its preferred embodiment thus integrates thebetter properties of lithium-type and lead acid-type cells in a hybridarrangement that also avoids their known shortcomings. The inventedsystem provides unprecedented long life via the primary cell andunprecedented high switching capacity via the secondary cell in anunprecedented small volume. This advantageous characteristic of theinvented system in its preferred embodiment will be referred to hereinas high energy density. In the alternative embodiments, thevoltage/current characteristics and capacities of various pairedcell-types are optimized for EC eyewear switching applications, some ofthem focused on extending useful battery life, others focused onavoiding battery recharge requirements, yet others focused on reducingbattery replacement cost and still others focused on minimizing frameand temple size for aesthetic reasons.

Other aspects of the invention include the provision of a unique hingeassembly, including a leaf spring defining an inner wall of a forwardregion of the battery tubes, connecting the eyewear's eyewires and eachtemple. They also include the provision in at least an inner region ofthe temple tips of a polymeric material for protecting the EC lenseswhen the temples are folded. Finally, they include the provision of anexternal battery charger case for supporting the EC eyewear and forcharging relatively short-lived batteries, e.g. a lead acid pair,without disassembly of the eyewear and with a ultra-low-powerannunciator to apprise the EC eyewearer of the charging status.

These and additional objects and advantages of the present inventionwill be more readily understood after a consideration of the drawingsand the detailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram of the invented battery power supplymade in accordance with its preferred embodiment, illustratively used inan EC lens converter circuit.

FIG. 2 is a cross-sectional plan view of one of the batteries of thehybrid battery subsystem.

FIG. 3 is a cross-sectional plan view of the other of the batteries ofthe hybrid battery subsystem.

FIGS. 4 and 4A are isometrical views of the hybrid battery subsystem ofFIG. 1, further including the invented controller, switch andinterconnect components, all fitted within a frame of a pair ofeyeglasses.

FIGS. 4B and 4C are detailed cross-sectional views of certain inventiveaspects of the eyewires shown in FIG. 4.

FIG. 5 is an isometric view of an external battery charger case for usewith the dual lead acid cell battery configuration.

FIG. 6 is a schematic circuit diagram of the external battery chargerwithin the case shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 schematically illustrates at 10 the invented power supply, orbattery/power management, system for providing primary and secondary(back-up) DC power to microelectronics such as electrochromic (EC)eyewear. The use of system 10 is not limited to eyewear, of course, aswill be appreciated by those skilled in the art. The invention isbelieved to be useful in any microelectronic application requiringrelatively long-term low-current standby DC power and relativelyshort-term high-current switchable DC power in a volume-restrictedspace.

Power supply system 10 preferably includes a controller 12 and a hybridbattery subsystem 14 (indicated in dashed outline) including a first orprimary battery 16 of a given cell type preferably including alithium-type cell, e.g. one having a composition chosen preferably fromlithium/thionyl chloride (LiSOCl₂) and lithium (poly-)carbonmonofluoride ((CF)_(n) /Li), and a second or secondary battery 18 of agiven cell type (different from the first cell type) preferablyincluding a sealed lead acid-type cell. Primary and secondary batteries16, 18 are operatively coupled by controller 12 and cooperate with oneanother in a hybrid arrangement to supply DC power to micro-electroniccircuitry such as an EC lens converter indicated generally at 20.

Controller 12 preferably includes a switch-mode DC power converter,indicated in FIG. 1 generally at 22, which is powered by first battery16 and which is capable of charging second battery 18. By its uniqueorganization including controller 12 and hybrid battery subsystem 14,system 10 meets stringent operating characteristics including 1)low-energy, high-current (pulse) drain requirements of at leastapproximately 60-130 mA for 5-10 seconds (as required to switch EClenses from clear to fully darkened at an acceptably fast rate) and 2)high-energy, low-current operating long life of greater than 6 months orapproximately two thousand cycles and a shelf life of greater thanapproximately one and one-half years (as required of quality, durable ECeyewear).

It is believed that this unique combination of two battery chemistriesbest matches the requirements of high energy density and best achievesaesthetic demands of micro-electronic applications such as solid-stateEC eyewear, yet is robust enough to provide both pulse dischargecapability and overall power capacity needed to power micro-electronicapplications such as EC eyewear lenses requiring fast, fullcolor-switching times (under five seconds) and high, fullcolor-switching cycle counts (more than fifteen hundred). The inventionthus provides unprecedented switching rate and extended life, ascontrasted with prior EC eyewear that manages full color switching inapproximately fifteen seconds for only approximately three hundredcycles.

Power converter 22 may be seen from FIG. 1 preferably to include avoltage reference 24 and an internal battery charger 26, connected asindicated to primary and secondary batteries 16, 18. System 10 as usedin the illustrated EC lens converter circuit may be seen preferably toinclude control logic 28 and a preferably switch-mode lens driver 30including full bridge-configured output transistors Q1, Q2, Q3, Q4 andtheir associated internal diodes providing bidirectional current flowand low voltage drop in either direction, lens driver 30 being connectedas indicated to at least one EC lens 32 (illustrated only schematicallyin FIG. 1) that may be mounted within an eyewear frame (not shown inFIG. 1, but shown in FIG. 4).

It will be understood by those skilled in the art that lens 32, like itscompanion, mirror-image, lens 34 (not shown in FIG. 1, but shown in FIG.4), is capable of switching its visible light transmissivity, e.g. atleast its transmissivity of light energy, within the visible frequencyspectrum, that is incident thereon, between approximately 15%transmissivity (referred to herein as a darkened condition of the lens)and approximately 70% transmissivity (referred to herein as a clear orbleached condition of the lens). It will be appreciated that ultravioletand other harmful, near-visible light components preferably are filteredby conventional means such as coating the EC lens. Thus, the inventionprovides the EC eyewearer with constant protection, as well as withmanually operable and thus selective comfort. Switching is accomplishedby the operation of one or more switches such as manually operableswitches S1, S2.

Various dual like-cell battery configurations are contemplated by theinvention, as alternatives to the hybrid-cell configuration describedand illustrated in detail herein. For example, it has been discoveredthat four silver oxide batteries such as those used in electronicwristwatch and camera applications may be used to supply switchingcurrent to EC lenses 32, 34. Alternatively, dual lead acid cells may beused, although such require frequent recharging, as will be described indetail below. In such dual, like-cell battery subsystems, form factorssimilar to that described above in reference to the hybrid-cell batterysubsystem are preferred, with like electromechanical temple tubingencasing, end capping and flex circuit interconnecting, as will bedescribed in detail below.

It will be appreciated that, in accordance with the preferred embodimentof the invention, two frame-mounted switches S1, S2 are provided formanual switching of both EC lenses between their bleached(high-transmissivity) and darkened (low-transmissivity) states. In suchembodiment, momentary closure of one of normally-open push-buttonswitches S1, S2 causes the lenses progressively to darken until theswitch is released, and momentary closure of the other of switches S1,S2 causes the lenses progressively to bleach until such other switch isreleased. If both of switches S1, S2 are depressed at once, the lensesprogressively bleach until the switches are released.

It will be understood from FIG. 1 that switches S1, S2 are logic-levelswitches that are electrically connected to logic inputs of controllogic 28, which switches simply ground otherwise high-logic levelsignals to indicate to control logic 28 that the user of the EC eyewearintends to change the transmissivity of its lenses. Thus, referencesherein to the connection of switches S1, S2 between controller 12 andlenses 32, 34 will be understood to refer to an operative, rather than aphysical, connection therebetween. Advantageously, this use of logiclevel switching, rather than of relatively higher-current switching oflenses 32, 34 by lens driver 30, renders it possible to use tiny-volumemembrane switches activated by tiny frame-mounted push buttons, as willbe described.

Those skilled in the art will appreciate that coded or uncodedplural-switch operations alternatively may be used, within the spiritand scope of the invention. For example, a single switch might bescanned and its closure and/or cycle time measured such that the timingand/or rate of closure determines the desired switching operation, as isknown in the field of wristwatches and other micro-electronicsapplications.

EC lenses 32, 34 may be of any known composition and lay-up compatiblewith the electro-mechanical configurations of the disclosed lensconverter and eyewear frame. Illustratively, lenses 32, 34 may be formedfrom laminar glass substrates, and may have active layers thereincapable of producing, upon the application of a DC potential at thelenses' edges, a desired change in transmissivity of near-visible light.U.S. Pat. No. 5,142,406 entitled ELECTROCHROMIC OPTICAL SWITCHING DEVICEand issued Aug. 25, 1992, with which familiarity is assumed, describesone such EC device and its operation. EC lens edge layer contact andisolation may be accomplished as taught therein or by any suitablemethod, e.g. via the selective application of a conductive compositionsuch as gold ink to a peripheral edge region of lenses 32, 34.Protective layers providing ultraviolet screening and reducing visiblelight reflection may be used, without departing from the spirit andscope of the invention.

An EC lens behaves somewhat like a large capacitor that is chargeable toa desired voltage level at which it passively remains for as long as thevoltage between its electrodes is maintained. This charge-maintainingcapacity is due primarily to relatively low lens leakage currents, whichmay be as small as approximately 1 μA. Those skilled in the art willappreciate that the choices of materials, processes, coatingthicknesses, etc. affect such EC lens performance characteristics,including series capacitance and resistance, leakage current, switchingtime, transmissivity range, stability and life expectancy.

The discrete devices and the voltage reference shown in FIG. 1 arebelieved to be readily understood by those of skill in the art, and maybe of any conventional design compatible with large-scale integration.Thus, for the sake of brevity, they are not described in detail herein.The control logic and lens driver shown in FIG. 1 will be understood bythose of skill in the art in detail by the description of the operationof switches S1, S2, and internal battery charger 26. It will beappreciated that lens driver 30 preferably is implemented as aswitch-mode DC power converter that may be quite similar to theswitch-mode DC power converter implementation of internal BATTERYCHARGER 26 to be described below.

Briefly summarizing the operation of power supply system 10 by referenceto the functional blocks of FIG. 1, the illustrated signals will bedescribed by reference to their signatures. V_(PRI) and V_(SEC)represent the positive terminals, respectively, of primary and secondarybatteries 16 and 18, suitably decoupled by corresponding externalcapacitors, as shown. V_(REF) represents a stable voltage levelestablished by VOLTAGE REFERENCE 24 as a function of V_(PRI). V_(REF) isdivided down by three series-connected external resistors to produceV_(LIMP) (a positive voltage reference level) and V_(LIMN) (a negativevoltage reference level) that are used by LENS DRIVER 30 to establish,respectively, the maximum and minimum operating voltages of lenses 32,34. Another external resistor is used to establish R_(LIM), which sets acurrent limit for LENS DRIVER 30. A precision external resistor isconnected to V_(PRI) to define R_(SEN), a signal used by internalBATTERY CHARGER 26 as a current limit in the hybrid battery subsystemconfiguration of invented power supply 10.

P_(GND) represents a ground reference for the preferred tile arrayimplementation of controller 12. V_(S2B) represents a secondary batteryvoltage-sense signal that essentially enables CONTROL LOGIC 28 to turnoff LENS DRIVER 30 if either lead acid battery of hybrid batterysubsystem 14 exhibits an under-voltage condition. L_(BAT) is produced byinternal BATTERY CHARGER 26 in hybrid battery system configurations thatinclude a lithium-type cell and is connected to V_(SEC) via an externalinductor, as shown in FIG. 1. Such external inductor, it will beunderstood, may be fitted within a corner block of the frame of eyewear38, as will be described by reference to FIGS. 4 and 4A.

Finally, P_(LIND) and P_(LENS) are produced by LENS DRIVER 30 for therespective drive and sense connections via one of the windings ofdual-wound inductor L1 with the lenses' positive electrodes, andN_(LIND) and N_(LENS) are produced by LENS DRIVER 30 for the respectivedrive and sense connections via the other winding of dual-wound inductorL1 with the lenses' negative electrodes. Those of skill in the art willappreciate that one or more lenses such as lenses 32, 34 connected inparallel with one another and with an external filter capacitor (seeFIG. 1) may be so driven by LENS DRIVER 30.

Internal BATTERY CHARGER 26 may be seen to form a part of what isreferred to herein as a switch-mode DC power supply, or converter, 22.BATTERY CHARGER 26 also may he seen to be operatively coupled withCONTROL LOGIC 28 and CONTROL CIRCUITRY, indicated generally at 36,thereby efficiently to transfer power from the secondary cell to EC lens32 and to act as a battery charger to trickle recharge secondary battery18 from primary battery 16. CONTROL CIRCUITRY 36 also cooperates withcontrol logic 28 to manage the color-switching control of the EC lens byway of LENS DRIVER 30 and switches S1, S2. Those of skill in the artwill appreciate that CONTROL CIRCUITRY 36 thus operates selectively tosupply power from the charger to the battery subsystem.

Preferably, the power supply within battery charger 26 is acurrent-limiting, step-down, or `buck`, switching regulator thatoperates discontinuously. In other words, the power supply of charger 26operates only when the EC lenses are not being charged by the controlcircuitry, e.g. lens driver 30. Also, the power supply stops chargingthe batteries when the charge voltage reaches nominally 2.26 V. Thepower supply accepts input voltages within the range between 2.6 V and4.4 V, thereby rendering it compatible with the various batteryconfigurations described herein. The power supply's output current intoa secondary, e.g. lead-acid cell, battery is approximately 500 μA at2.25 V and 25° C. The external output inductor shown in FIG. 1 ispreferably approximately 750 μH, and may exhibit a series resistance ashigh as approximately 25 Ω. Importantly, the power supply's efficiencyis greater than approximately 70-80%, as measured with a primary batteryvoltage of 3.5 V and secondary battery voltage of 2.2 V.

Lens driver 30 preferably acts as a constant-current source, withvoltage limits compatible with charging an EC lens such as lenses 32, 24to a desired voltage level representing a desired visible-lighttransmissivity. Preferably, lens driver 30 is implemented as afour-quadrant switching power converter including quad, full-bridgeconfigured output transistors providing bidirectional current flow andlow voltage drop in either direction. The preferred implementation oflens driver 30 employs at its output a dual wound differential inductorL1 that forms a part of an L-C output filter (for producing a smoothoutput waveform and preferably approximately smooth, linear switchingoperation of EC lenses 32, 34).

In accordance with the preferred embodiment of the invention, bipolarcomplementary metal oxide semiconductor (BICMOS) is used to implementthe power supply and control circuitry functions described herein inwhat is referred to in the chip design field as a tile array. Such a lowon-resistance semiconductor fabrication process provides the desireddesign flexibility, tiny volume, low power, long life, cool operationand stable operation that is demanded by many micro-electronicapplications including quality EC eyewear. Those of skill in the artwill appreciate that alternative circuit and chip design and fabricationprocesses may be used, so long as they are capable of achieving thedesired functional density that is required in meeting the aestheticdemands of eyewear consumers.

Those of skill in the art will appreciate that such control circuitrymay in alternative embodiments include internally masked or externallyprogrammable logic or jumpers that determine what battery configurationis present and provides the suitable charging current and voltage viaBATTERY CHARGER 26 to the battery subsystem when lens driver 30 isinoperative, i.e. when the batteries are not being used to switch orpower EC lenses 32, 34. It will be appreciated that such externalresistors, as well as other external components, may be integrated alongwith their associated power supply and control circuitry, thus furtherto reduce circuitry volume and further to increase functional density.

The invented hybrid-battery power supply may be described, for use in ECeyewear, as including first and second batteries 16, 18 having alithium-type cell and a lead acid-type cell, respectively, andcontroller 12 for operatively connecting the same to one another and toEC lens 32. Controller 12 preferably includes switch-mode powerconverter 22 that, powered by first battery 16, is capable of chargingsecond battery 18. Controller 12 may be seen from FIG. 1 to beresponsive, while being powered by first battery 16, to one or moremanually operable switches S1, S2 connected with the EC eyewear tosupply power from second battery 18 to EC lens 32 via lens driver 30.Persons skilled in the art will appreciate that the inventedhybrid-battery power supply lends itself to numerous alternativeapplications, all within the spirit and scope of the invention.

FIG. 2 shows primary battery 16 in a cross-sectional plan view thatillustrates its advantageous form factor and functional density. Primarybattery 16 preferably takes the form of a lithium-type cell thatprovides at least approximately 200 mA-hours' energy capacity, whichsatisfies the long cycle or operating life requirement, e.g. more thanapproximately six months, and the long shelf life, e.g. more thanapproximately one and one-half years, of EC eyewear and similarlydemanding micro-electronic applications. Primary lithium thionylchloride battery 16 occupies a volume preferably of less thanapproximately 1.0 ml, more preferably of less than approximately 0.8 mland most preferably less than approximately 0.65 ml. Such a tiny volumeis achieved by the illustrated chemistry, cell and electrodesconfiguration, and preferably battery 16 is housed in a substantiallysealed, preferably metal, canister.

It may be seen from FIG. 2 that primary lithium thionyl chloride battery16 preferably is elongate and of generally uniform, e.g. rectilinear andmore preferably right-rectangular, cross section. It also may be seenthat primary battery 16 preferably has a length (L)-to-width (W) ratioof at least approximately 5:1, more preferably at least approximately7:1 and most preferably at least approximately 8:1.

FIG. 3 shows secondary battery 18 in a cross-sectional plan view thatsimilarly illustrates its advantageous form factor and functionaldensity. Secondary battery 18 takes the form of a lead acid cell thatprovides at least approximately 10-20 mA-hours' energy capacity, whilealso meeting the long operating and life requirements of, for example,EC eyewear. Secondary lead acid battery 18 occupies a volume preferablyof less than approximately 1.0 ml, more preferably of less thanapproximately 0.8 ml and most preferably less than approximately 0.65ml. Such a tiny volume is achieved by the illustrated chemistry, celland electrodes configuration, and preferably battery 18 is housed in asubstantially sealed, preferably metal canister.

It may be seen from FIG. 3 that secondary lead acid battery 18preferably is elongate and of generally uniform, e.g. rectilinear andmore preferably right-rectangular, cross section. It also may be seenthat, like primary battery 16, secondary battery 18 preferably has alength (L)-to-width (W) ratio of at least approximately 5:1, morepreferably at least approximately 7:1 and most preferably at leastapproximately 8:1. Importantly, secondary lead acid battery 18 has apulse current capacity of at least approximately 60-130 mA for at leastapproximately 3-5 seconds, and preferably for at least approximately10-15 seconds, i.e. long enough to fully color switch the EC lenses.

This battery characteristic uniquely achieves the high pulse currentdrain requirements of EC eyewear and similarly demanding applicationswherein user-responsiveness to switching the state of themicro-electronics must be relatively fast, e.g. no more thanapproximately 5-15 seconds. Those of skill in the art will appreciatethat it is preferable to provide EC eyewear having a substantiallysymmetric switching time, whether from bleached to dark or dark tobleached. While prior EC eyewear may achieve relatively short, e.g.approximately 5 second, switching times from bleached to dark, theyrequire much longer, e.g. approximately 15 second, switching times fromdark to bleached. The present invention achieves substantiallysymmetric, and relatively shorter, e.g. approximately 5-10 second, fullcolor-switching times, regardless of the starting state of the EClenses.

FIG. 4 shows the illustrated application of the invented system whereby,in accordance with the preferred embodiment thereof, the tiny volumethat has been achieved is approximately 4 mm×4 mm×40 mm=640 mm³ each forthe hybrid, lithium and lead acid battery packages for a total volume ofslightly over 1 ml for the illustrative EC eyewear application. It maybe seen from FIG. 4 that the form factors of first and second batteries16, 18 preferably are approximately equal, and that the first and secondbatteries occupy volumes that are approximately equal to one another.Such lends the invented hybrid battery subsystem to applications such asEC eyewear in which extremely limited space is available and in whichsuch limited space is approximately equally divided. It also may seenthat, for such eyewear applications, first and second batteries 16, 18also preferably are substantially symmetrically located within eithertemple of the eyewear, thus freeing other areas of the eyewear for othermicro-electronics such as controller 12, control logic 28 and lensdriver 30.

Summarizing now, by reference still to FIG. 4, the invented EC eyewear,indicated generally at 38, may be seen preferably to include an eyewearframe such as eyeglass frame F; an EC lens such as lens 32 and/or lens34 mounted therein, with the lens being capable of switching its visiblelight transmissivity; one or more switches such as manually operableswitches S1, S2 also preferably mounted therein, with at least one ofthe switches being operatively connected to the lens; and a power supplysuch as hybrid battery power supply 10 preferably contained within theframe. Such power supply preferably includes a controller such ascontroller 12; a first battery such as primary lithium-type battery 16for supplying standby current to the controller; and a second batterysuch as secondary lead acid-type battery 18 for supplying switchingcurrent through the connected switch to the lens. Preferably, thecontroller includes a switch-mode power converter such as powerconverter 22 capable of charging the second battery, as described andillustrated herein.

It may be seen from FIG. 4 that first and second batteries of whatevercell type, in accordance with the preferred embodiment of the invention,are symmetrically located on either side of frame F immediately behindlateral hinge assemblies 40, 42 that connect their respective temples44, 46 to frame F. For aesthetic and safety reasons, each battery isenclosed within a battery sleeve or tube such as mirror image tubes 48,50. Each battery is sealed within its respective tube, and iselectrically connected to a flex circuit 52 by a battery tube end capsuch as end caps 54, 56, which provide sealing enclosure of thebatteries to prevent leakage from reaching the exterior of the eyewearand to prevent moisture from reaching the interior thereof. One suitablemeans for sealing lead-acid batteries within battery tubes involves theuse of a metal-filled, e.g. lead-filled, polymer glue as a sealant.

A unique feature of invented EC eyewear 38 is applicable not only to ECeyewear, but is believed to be useful in eyewear applications generally.Invented hinge assemblies 40, 42 preferably are provided hingedly toconnect rearwardly extending temples 44, 46 with laterally spacedregions of dual eyewires 58, 60 such that the eyewear, e.g. EC eyewear38, easily and conveniently can he deployed and stowed. Mirror-imagehinge assemblies 40, 42 include first hinge members 62, 64 projectingrearwardly from a lateral region, or corner block, of a correspondingeyewire such as bridge-connected eyewires 58, 60, and a hingedly matableforward terminal end of a corresponding temple such as temples 44, 46,with interleaving fingers thereof being pivotally securable by a pinextending through aligned holes thereof, as is known.

Importantly, and referring now to FIGS. 4 and 4A, invented hingeassemblies 40, 42 include in a forward region of temples 44, 46corresponding leaf springs 66, 68 that lie nominally in a plane of aninner wall of a corresponding tube such as tubes 48, 50 and that forms aforward, terminal extent thereof. Forward, terminal ends of leaf springs66, 68 will be understood to be capable of being temporarily deflectedoutwardly from their nominal position of co-planarity with the outerside walls of tubes 48, 50 by forces exerted thereon by one or more ofthe fingers of rearwardly projecting members 62, 64 of eyewires 58, 60.As may be seen from FIG. 4, outer expanses 70, 72 of members 62, 64 eachdefine a first generally flat surface region of the projection, e.g.surface region 62a of member 62, that acts as a cam surface followed bythe corresponding, resiliently deflectable leaf spring, e.g. leaf spring66.

The cams and cam followers, which are defined for example by leaf spring66 formed within temple 44 and region 62a of corresponding projectingmember 62 of eyewire 58, are configured to ensure that, when the temples44, 46 pivotally are overextended such that their rearward extreme ends44a, 46a are maximally spaced from one another, they are urged or biasedto return to a nominally 90° pivotal orientation relative to the planeof eyewires 58, 60.

Preferably, projections 62, 64 further include second flat regions 62b,64b that each also act as camming surfaces when the eyewear is foldedinto what will be referred to herein as a stowing condition thereof inwhich the eyewear is Generally flat. In accordance with this feature ofthe invention, leaf springs 66, 68 act as cam followers to bias or urgetemples 44, 46 into such stowing condition, while providing protectionfor lenses 32, 34 from inadvertent and potentially damaging impact bytemple tips, or extreme rearward temple ends, 44a, 46a. Second flatregions 62b, 64b will be understood to be located on projections 62, 64such that leaf springs 66, 68 lie flat thereagainst in a nominallyclosed condition of the eyewear in which the temple tips do not touchthe corresponding lenses, e.g. EC lenses 34, 32, to which they areclosely proximate.

The invention in one broader aspect now may be appreciated to be a pairof eyeglasses including a front piece 72 and a temple, or temple piece,such as temple piece 44 having a top surface 44b, a bottom surface 44cand a leaf spring 66 defining a side surface 44d of the temple piece,with the leaf spring being movable relative to the top and bottomsurfaces to bias the temple piece into a predetermined open positionindicated in FIG. 4 from an overextended open position, as is known,relative to the front piece.

Preferably, such front piece 72 includes structure 74 for receiving alens such as lens 32 therein and a cam surface 76 operatively connectedwith, and projecting rearwardly from, the structure, wherein the templepiece is hingedly connected to the cam surface, as suggested by FIGS. 4and 4A. Also in accordance with the preferred embodiment, cam surface 76includes a flat region 76a cooperable with the leaf spring thereby tobias the temple piece into such predetermined open position, also asshown. Finally, it is preferable that cam surface 76 includes a secondflat region 76b cooperable with the leaf spring thereby to bias thetemple piece into a folded position relative to the front piece.

By another aspect of the invented eyeglasses pair, temple piece 44further includes a first end 44e hingedly connected to front piece 72and a second end 44a including a region 44f (refer also to region 46f oftemple piece 46) of protective coating to reduce or preferably eliminatelens scratching when the temple piece is in such folded positionrelative to structure 74. This coating preferably is selectively formedin a distal, or rearward terminal, region of temple piece 44 as byselectively dipping a terminal end of temple piece 44 in a liquidurethane bath. Those of skill in the art will appreciate that suchprotective coating may be selectively formed to a greater or lesserextent, or may take thicker or thinner forms and may be formed ofdifferent materials that provide the desired resilient, non-abrasiveprotection for the lenses of the eyeglass pair, all within the spiritand scope of the invention.

Another important aspect of the invention focuses on the frame itself.Such an eyeglass frame F as is shown in FIGS. 4 and 4A may be seen toinclude a front piece 72 including structure 74 for receiving a one ormore lenses such as lens 32 therein, with the structure defining a firstplane indicated at P₁ and with what will be referred to herein as acorner block 78 projecting laterally and rearwardly from the structure;and a temple piece 44 connected to the corner block, with the templepiece including a side wall 44g defining a second plane indicated at P₂and leaf spring 66 defining a forward extension of the side wall suchthat the leaf spring lies substantially within such second plane. Such aleaf spring-equipped hinged corner assembly in a pair of eyeglasses isreadily seen to provide unprecedentedly lightweight, hollow corner andtemple piece structure that is compatible with aesthetic and functionaldemands placed upon not only the invented electrochromic eyewear butalso upon conventional eyewear.

Preferably, the invented frame features symmetrically located cornerblocks such as corner block 78 (formed as illustrated in upper and lowermating pieces the lower of which will be referred to herein as a rimlockmember) including a flat region such as previously described flat region62a of member 62 cooperable with the leaf spring thereby to bias thetemple piece into a predetermined open position relative to the frontpiece. Preferably, each corner block includes a second flat region suchas previously described flat region 62b of member 62 cooperable with theleaf spring thereby to bias the temple piece into a folded positionrelative to the front piece such that first plane P₁ is substantiallyparallel with second plane P₂. Of course, it is typical for the frontpiece to include one or more lenses positioned within correspondingeyewire regions of structure 74. Thus, it is preferable for the templepiece to include at least an inner region 44f of resilient, e.g.elastomeric, coating positionable adjacent such lens when the templepiece is in a folded position. In this way, the coating prevents damageto the lens(es) that otherwise may be caused by pivoting of the templepiece into a closed, or flat, configuration of the eyewear, e.g. forstowage.

The invented optical frame assembly alternatively may be described asfollows, again by reference to FIGS. 4 and 4A. The frame assembly may beseen to include a front piece 72 including structure 74 for receiving alens such as lens 32 therein, with the structure defining a first planeP₁, and a projection 80 attached to, and preferably integrally connectedto, the structure and extending outwardly or rearwardly such that theprojection 80 extends transversely relative to first plane P₁. The frameassembly also may be seen to include a temple member 44 defining asecond plane P₂, with the temple member including a front region 44ehaving a side subregion 44g and a rear region 44a, the front regionbeing pivotally mounted to the projection such that the temple memberand the front piece define an angle θ therebetween, and such that saidtemple member is movable between a folded position wherein θ equalsapproximately 0°, a predetermined open position indicated in FIG. 4wherein θ equals approximately 90°, and an overextended open position,as is known, wherein θ is greater than 90°.

Front region 44e further may be seen, perhaps best by reference to FIG.4A, preferably to include a leaf spring 66 extending within the plane ofthe side subregion when the temple member is in such predetermined openposition or such folded position, with the leaf spring and theprojection cooperating to bias the temple member into the illustratedpredetermined open position from the illustrated overextended openposition. Preferably, projection 80 includes a first flat region such aspreviously described region 62a of member 62 cooperable with leaf spring66 thereby to bias the temple piece into such predetermined openposition from such overextended open position. Also, preferablyprojection 80 includes a second flat region such as previously describedregion 62b of member 62 cooperable with leaf spring 66 thereby to biasthe temple piece into such folded position.

From FIG. 4A, those of skill in the art will appreciate that thesymmetrically located right-cylindrical recesses formed in the upper andlower pieces of the corner blocks provide for the inclusion in powersupply system 10 of further external components such as the externalinductor described and illustrated in connection with FIG. 1. Such, itwill be appreciated, are interconnected in accordance with invention,via flex circuit 52, suitably modified as needed to accommodateadditional signal routing via printed flexible circuit conductors. Thoseof skill in the art also will appreciate that eyewires 58, 60 may inalternative embodiments preferably are in the form of open loops, asillustrated by the through cut in the lateral, outer regions thereof, toenable removal and insertion of EC lenses 32, 34, with only minimaldisassembly of eyewear 38. Modifications to hinge assemblies 40, 42 thatfurther facilitate lens removal and insertion are within the spirit andscope of the invention.

Of course, in accordance with the preferred embodiment of the inventedframe assembly, front piece 72 includes a lens positioned within thestructure for receiving a lens, whether of the conventional or ECvariety, whether prescription or not. As described above, preferablyrear region 44a of the temple member includes an illustratednon-abrasive coating to reduce, and to the greatest extent possible toeliminate, lens scratching by the temple member. Those of skill in theart will appreciate that these improvements in eyewear frame assembliesare broadly applicable to conventional eyewear as well as to theinvented EC eyewear illustrated herein, as will be described in moredetail below.

In the EC eyewear context, the invention in one of its important aspectsmay be described as a pair of electrochromic eyeglasses including 1) afront piece 72 including two eyewires, or electrochromic-lens-receivingsupports, 58, 60 and a hollow bridge 84 connecting the supports, withthe supports each including a recess such as recesses 58a, 60a extendingaround an internal surface of the supports' periphery, with each recessbeing configured for holding an electrochromic lens such as lenses 32,34; 2) temple members 44, 46 connected to either side of front piece 72by a corresponding hinge such as hinge 40, with each temple memberincluding an elongate chamber such as chamber 88 defined within tube 48for enclosing a battery such as any of those described herein; and 3) aflex circuit assembly 90 (including flex circuit 52 as well as theabove-described components mounted thereon) fitted within front piece72, the circuit assembly including a proximal active-component circuitregion 92 (in which such components are mounted) for driving theelectrochromic lenses.

Preferably, as is suggested by FIG. 5, the circuit assembly includesplural-conductor regions 94, 96 extending from the active-componentcircuit region in generally opposite directions for routing through thesupport recesses, around the eyewires for connection with the lenses andswitches formed thereabout, through the hinges and at least partway intothe chambers for electrical connection of batteries contained thereinwith the active-component circuit region of the flex circuit assembly.Those of skill in the art will appreciate from FIG. 4 the manner inwhich illustrated flex circuit 52 in its unfolded form external to frontpiece 72 and temples 44, 46 in its assembled form has expanses 94, 96are routed through channels 58a, 60a, through hinge assemblies 40, 42and endcaps 54, 56 into tubes 48, 50 for connection with primary andsecondary batteries 16, 18 to render EC eyewear 38 operative.

Also preferably, flex circuit assembly proximal region 92 is positionedwithin bridge 84, as described and suggested by the exploded assemblydrawing of FIG. 4. It is the form friability of this proximal, mostpreferably substantially central, region wherein both integrated anddiscrete circuit components are interconnected that gives EC eyewear 38made in accordance with its preferred embodiment its functionality andaesthetics.

With further regard to flex circuit assembly proximal region 92 in whichthe power supply and controller circuitry is assembled and preferablypotted, it will be appreciated that a printed circuit board (PCB), e.g.so-called FR-4, is used in one exemplary embodiment, while it is withinthe spirit and scope of the invention to mount the circuitry directly tothe flex circuit in region 92 by the use of techniques similar to thoseof known surface mount technology (SMT). The advantage of mounting thecircuit components on a PCB and, in turn, mounting the PCB on the flexcircuit in region 92--by a process that is analogous to knownchip-on-board hybrid circuit fabrication--is design flexibility andadaptability to any one of various battery subsystems that might beavailable or desirable and ease and low cost of manufacture.

As may be seen from FIG. 4, flex circuit assembly 90 preferably furtherincludes in plural-conductor regions 94, 96 thereof lens-contacting landregions 98, 100 for operative electrical connection with one suchelectrochromic lens such as lens 32. Those skilled in the art willappreciate that preferably lens-contacting regions 98, 100 are formed ofgold-plated copper, thereby to ensure reliable electrical contact and toreduce the tendency of the copper to corrode, especially under humidconditions. Skilled persons also will appreciate that elastomericconductive strips or pads may be used to great advantage between thelenses' edges and so-called "lens-contacting" regions 98, 100 to providein this region of electrical contact increased reliability anddurability. Such strips are available, for example, from Shin-EtsuPolymer America, Inc. in the form of a "Shin-Flex MAF-Connector", orsimilar anisotropic connector sheet.

Preferably, each of illustrated recesses 58a, 60a has substantiallyenclosed lengthwise peripheral regions such as region 58aa of recess 58a(refer momentarily to FIG. 4B) for capturing the flex circuit assemblywithin such supports, as well as substantially open regions such asregion 58ab (refer momentarily to FIG. 4C) interposed the enclosedperipheral regions for providing such electrical contact between lensespositioned within the supports and the land regions of the flex circuitassembly. Such interspersed flex circuit capture and access regionsprovide reliable electrical contact while rendering EC eyewear 38 easilyand inexpensively manufactured.

Referring still to FIG. 4, the laterally spaced manually formable templetips are provided immediately behind their respective battery tubes 48,50 to contribute to the formation of the eyewear's temples, indicated at44, 46. Importantly, in accordance with the preferred embodiment of theinvention, the temple tips are coated at least in a rearward, innerregion thereof with a non-abrasive, somewhat compliant, e.g. polymeric,material that protects the lenses from wear or damage when temples 44,46 are folded against, or otherwise inadvertently are made to contact,the lenses. In one embodiment of the invention, such coated regions oftemples 44, 46 are formed by dipping at least approximately 3.8 cm (1.5inches) of the terminal regions thereof in a liquid urethane bath toproduce a thin, protective, outer layer that resists abrasive orhigh-impact contact between the temple tips and the lenses.

Referring more specifically now to invented EC eyewear 38, a flexcircuit 52 may be seen to be used to interconnect end caps 54, 56 andtheir connected batteries with switches S1, S2 and the power supply andcontroller electronics disposed within a bridge 84 that interposes andconnects right and left eyewires 58, 60. Preferably, as shown in FIG. 4,controller electronics including all components shown in FIG. 1 exceptbatteries 16, 18 switches S1, S2, lenses 32, 34 and the distal regionsof flex circuit 52 are configured and sized to be contained withinbridge 84. In accordance with the preferred embodiment of the invention,it has been demonstrated possible to micro-miniaturize such controllerelectronics, including relative large inductor L1, and to fix the samein potting compound to form-fit it within the tiny volume, e.g. lessthan approximately 0.18 ml, of an interior void formed within bridge 84,as will be described in more detail below.

As illustrated in FIG. 4, all remaining components also are miniaturizedand formed to fit within voids and channels formed within the frame ofeyewear 38. The result is a lightweight, aesthetically pleasing pair ofEC eyeglasses compatible with non-prescription as well as prescriptionEC-coated lenses. The high transmissivity-switching speed andtransmissivity range, as well as the durability, achieved in inventedlightweight EC eyewear 38 is unprecedented. Importantly, the variety ofbattery options made possible by the invented cell configurationscomprehended by the invented micro-electronic controller renders ECeyewear 38 made in accordance with the invention extremely flexible andadaptable to future developments in microelectronics battery power.

Those skilled in the art will appreciate that relatively low-capacitybattery configurations also are accommodated by the invention. Forexample, an even lighter weight and smaller frame, for persons ofsmaller build, are possible with the described dual lead acid batteryconfiguration in which the lead acid cells may be made of approximatelyone-half the length of that shown in FIG. 4. Although such a batterysubsystem requires frequent charging, such is made possible by theexternal battery-charging EC eyewear case that is described below byreference to FIGS. 5 and 6. Such lead acid battery-powered EC eyewearrequires periodic, e.g. daily, recharging, which may be accomplishedvery simply by fitting the assembled eyewear within the case asdescribed and illustrated below. Thus, EC eyewear frames of variousweights and sizes will be seen to be within the spirit and scope of theinvention.

Importantly, FIG. 4 shows aspects of the invented micro-electronic powermanagement system including invented flex switches S1, S2 and inventedflex circuit 52. Flex circuit 52 including SMT-mounted circuitcomponents on a tiny FR-4 PCB is employed in accordance with theinvention for power and signal distribution in lieu of one or morelarger PCBs and wiring harnesses due to the volume restrictions imposedon EC eyewear frames. Similarly, flex switches S1, S2 are employedinstead of conventional push-button microswitches so to increase usercomfort and convenience in operating the switches to switch the EClenses between their polar transmissivity states.

Importantly, in accordance with the preferred embodiment of theinvention, switches S1, S2 are integrally formed as a part of flexcircuit 52, thereby avoiding a mechanical interconnection therebetweenand attendant weight and cost increases and a reduction in reliability.Also by the preferred embodiment, switches S1, S2 are configured to besandwiched between an eyewire and a bevel-flattened edge region (notshown, in FIG. 4, for the sake of clarity and simplicity) of its heldlens, preferably in spaced upper regions thereof. While not illustratedin detail in FIG. 4, the detailed structure of switches S1, S2 will beunderstood preferably to include a post having an enlargedswitch-depression end, with the post extending through the holes inframe F of eyewire 58 into enlarged endcaps that act as the externallyaccessible push buttons that are shown. The holes through which theposts extend may be sealed, if desired, by an O-ring gasket beneath theenlarged push button end of the switches. Operation of the switches toswitch the lenses requires only momentary, minimal effort on the part ofthe wearer by way of relatively light gripping pressure by which theswitches individually or collectively, e.g. simultaneously, may beactuated. Thus, switching of the lenses of the EC eyewear contactpressure in one or both contact pressure in one or both of two spacedregions of the frame, e.g. in the vicinity of frame-mounted push buttons102, 104 but requires little or no thought or effort.

Either one of, and preferably both of, switches S1, S2 then acts inaccordance with the invention as an operatively connected switch formedbetween eyewear frame F and one or both of EC lenses 32, 34, with theconnected switch including a first flexible, conductive (e.g.gold-plated copper) expanse such as expanse 102a adjacent frame F and asecond flexible conductive expanse such as expanse 102b adjacent the oneor both lenses. Such first and second expanses 102a, 102b are pre-formednormally (as by folding them into a lapped position during assembly) toproduce a first condition of the connected switch corresponding to afirst defined transmissivity of lenses 32, 34 and to produce undermanual pressure on frame F a momentary second condition of the switchcorresponding to a second defined transmissivity of lenses 32, 34.

As noted, in the preferred embodiment of the invention and for thepurpose of positive and unambiguous, intended rather than incidental,actuation thereof, two or more of such lens-connected switches aremounted in frame F, with such two switches being operatively connected(via control logic 28, refer momentarily to FIG. 1) to one or bothlenses 32 and 34, wherein each of the switches is formed between eyewearframe F, or more particularly an eyewire such as eyewire 58, andcorresponding EC lens such as lens 32, with each of such switchesincluding a first flexible conductive expanse 102a adjacent frame F anda second flexible conductive expanse 102b adjacent the lens.

As may be seen by momentary reference collectively to FIGS. 1 and 4,first and second expanses 102a, 102b preferably are pre-formed (uponassembly of EC eyewear 38) normally to produce a first condition, e.g.open or non-conductive, of each or both of switches S1, S2 correspondingto a first defined transmissivity, e.g. greater than approximately 70%,of the lens and to produce under manual pressure on, e.g. a push button102 mounted in, frame F a momentary second condition, e.g. closed orconductive, of each or both of such switches corresponding to a seconddefined transmissivity, e.g. less than approximately 15%, thereof.Expanses 104a, 104b are similarly formed to produce second push button104.

As is suggested by FIG. 4, switches S1, S2 disposed within eyewire 58are operable by manual gripping pressure on frame F, e.g. on eyewire 58in the vicinity of push buttons 102, 104, in at least two spaced regionsof frame F to actuate lens driver 30 via control logic 28 responsive toclosure of one or both switches. Each operatively connected switch, inaccordance with the preferred embodiment of the invention and by virtueof its implementation as a flex circuit, is responsive to such manual,e.g. push button, pressure optimally believed to be approximately fiveounces. Within the spirit and scope of the invention, switches S1, S2and corresponding push buttons 102, 104 may be located elsewhere in theframe, e.g. in the vicinity of the illustrated corner blocks or on thetemples. Also within the invention, switches S1 and S2 may beimplemented more conventionally, e.g. electronic, e.g, touch-sensitive,or electromechanical, e.g. microswitch, devices may be used.

A mere brush of the wearer's hand in the vicinity of either of switchesS1, S2 will not inadvertently actuate them to switch the transmissivityof the EC lenses, while the slightest intended gripping of frame F, e.g.in the vicinity of push buttons 102, 104 reliably will switch thelenses, thereby producing easily but firmly controllable operation ofthe EC eyewear. Moreover, such pressure as might inadvertently impact onswitches S1, S2 in the event that EC eyewear 38 is laid upside-down on aflat surface is insufficient to switch the transmissivity of lenses 32,34. Accordingly, inadvertent switching is avoided in foreseeablesituations.

Each of switches S1, S2 may be seen to include plural, e.g. dual,elongate, flexible circuits or conductor expanses 102a, 102b extendingalong frame F and around lens 32, with the flexible circuit havingpre-formed therein (upon assembly of EC eyewear 38) at least twooverlapping conductive termini such as termini 102a, 102b forming thedual contacts of the respective connected switch. Termini 102a, 102b maybe seen to be disposed in a first lapped relationship between frame Fand lens 32, thereby defining a first, e.g. open, condition of therespective connected switch. On the other hand, termini 102aa, 102ba ina second lapped relationship therebetween with external manual pressureapplied will be understood to define a second, e.g. closed, condition ofthe respective switch, thereby enabling such switching of thetransmissivity of the one or more lenses such as lens 32 (via CONTROLLOGIC 28 and LENS DRIVER 30 responsive thereto).

In accordance with the preferred embodiment of the invention, controller12--including all of internal BATTERY CHARGER 26 (including POWERCONVERTER 22 and CONTROL CIRCUITRY 36), CONTROL LOGIC 28 and LENS DRIVER30 for driving a pair of EC lenses 32, 34--are integrated into a singleintegrated circuit (IC) dimensioned to be less than approximately 0.18mm by 0.28 mm (70 mils by 110 mils). The IC and external discretecomponents including the variously illustrated resistors and capacitorsthen are adhered--either directly or on a carrier such as the disclosedtiny PCB--to a proximal, and preferably central, region of flex circuit52. The only non-integrated component of the microcontroller, i.e.inductor L1, is soldered to solder pads provided on the PCB. Controller12 including its external, integrated passive components and inductor L1thus is contained within a tiny volume of preferably less thanapproximately 0.15 ml, more preferably less than approximately 0.10 ml,even more preferably less than approximately 0.05 ml and most preferablyless than approximately 0.025 ml, thereby providing extremely highfunctional density in microelectronic applications such as theillustrative EC eyewear.

Such a tiny volume for the microcontroller described immediately aboveprovides advantages of functional density and low-power efficiency thatis unprecedented in microelectronics. Such is fittable within bridge 84of EC eyewear 38 very simply by potting it into potting compound withinthe void formed in the eyewear's bridge. A bridge cover (not shown)optionally may be provided to enclose this circuitry within bridge 84.As may be seen from FIG. 4, bridge 84 preferably is provided with dualexternal electrical contacts 106, 108 for the series-connected duallead-acid cell, or other suitable rechargeable-cell, batteries of one ofthe disclosed battery subsystems, for external charging by a batterycharging eyewear case now to be described.

Turning collectively now to FIGS. 5 and 6, it may be seen that FIG. 5 isan isometric view of an eyewear case 1 10 that securely and protectivelycradles and covers eyewear 38' (wherein it will he appreciated thateyewear 38', not shown for the sake of simplicity and clarity, may beidentical with eyewear 38 described and illustrated above as beingpowered by dual lead acid batteries) while charging its batteries. Thoseskilled in the art will appreciate that case 110 may take anyutilitarian and ornamental form, as suggested by its dashed outline.Importantly to this external battery charger aspect of the invention ismeans by which eyewear 38' is grippingly engaged adjacent its bridge 84such that its dual batteries, e.g. dual lead acid batteries 16, 18 arecharged, without even partial disassembly of eyewear 38' being required.

Preferably, what will be referred to herein as battery contact means orstructure indicated at 112 includes mechanical bridge-gripping structure114 and a pair of electrical contacts or regions 116, 118 configured formatingly electrically engaging corresponding battery circuit contacts orregions 106, 108 of eyewear 38'. Preferably, bridge-gripping structure114 is formed of a polymer casting 120 into which a generally C-shapedspring clip 122 is insert molded, as shown. Those of skill in the artwill appreciate that such bridge-gripping structure may take any of avariety of forms, and may be formed by any suitable means, to provide,within the spirit and scope of the invention, for the secure gripping ofbridge 84 of EC eyewear 38'.

Operatively connected to electrical contacts 116, 118 and preferablylocated within eyewear case 110 is an external battery CHARGER circuit124 packaged in any suitable form, as by a discrete or integratedcircuit (IC) devices interconnected as by use of a PCB powered by abattery B₁. It will be appreciated that any suitable electromechanicalstructure may be provided, within the spirit and scope of the invention.

Referring now specially to FIG. 6, the operation of external batteryCHARGER circuit 124 will be described, with the CHARGER portion of thecircuit described first. In accordance with the preferred embodiment, areplaceable 9 V battery B₁ is connected across the negative SHDN(shutdown) and positive VCC (supply) inputs to a conventional voltageregulator/supply IC 126 such as a ICL7663 (a CMOS programmable"micropower" linear voltage regulator) available from Maxim IntegratedProducts, Inc. of Sunnyvale, Calif. or from Harris Semiconductor ofMelbourne, Fla. Preferably, regulator/supply IC 126 is temperaturecompensated by connecting the VTC (voltage temperature compensation)input through a resistor R1 to a sense voltage divider comprisingresistors R2, R3 and a potentiometer K1. Such establishes, in accordancewith a preferred embodiment of the invention, an approximately -25mV/°C. temperature compensation factor, although of course any suitablesetting may be used.

It will be understood from the circuit diagram that series-connectedlead acid batteries 16, 18 within eyewear 38' are connected across suchvoltage divider to the SENSE input of regulator/supply IC 126 wheneyewear 38' is placed within case 110. As shown in FIG. 6, the VOUT1 andVOUT2 outputs of regulator/supply IC 126 are connected via a resistor R4to the sense line, which also is connected to VCC via a resistor R5.

In one preferred embodiment of the invention, preferably precision (≦1%)resistors R1, R2 are 2.7 megohm (MΩ) and preferably precision resistorR3 is 1.0 MΩ. In that embodiment, R4 is 470 Ω and R5, K1 are 100 kilohm(kΩ). Potentiometer K1 will be understood to provide an adjustable floatcharge voltage between contacts 116, 118 for charging the lead acidbatteries within eyewear 38 at a desired current and voltage. The use ofa battery B₁ renders battery CHARGER within case 110 portable, and theuse of a replaceable battery renders the same easily and inexpensivelymaintained. Those of skill in the art will appreciate that, within thespirit and scope of the invention, different battery charger circuittopologies, and/or alternative component types and values, may be used.

The SENSE input to regulator/supply IC 126, which is connected to thepositive one of contacts 116, 118 and thus represents the output, orcharging, current line, and with a connected lead acid battery pairthereat also represents the output thereof under load, is connected viaresistors R6, R7 as shown to the positive input of a first operationalamplifier (op amp) A1. The negative input of first op amp A1 isconnected to the VTC input to regulator/supply IC 126. Thus, op amp A1and its closely associated support circuitry act as a load voltageCOMPARATOR to detect when a connected lead acid battery pair presents aload to external battery CHARGER, i.e. to detect when external batteryCHARGER is charging the eyewear's lead acid batteries.

The output of first op amp A1 is connected through a filter networkcomprising a series resistor R8 and VCC-biased capacitor C1 to thepositive input of a second op amp A2 the negative input of which isconnected via resistor divider comprising resistors R9, R10 between VCCand ground. First and second op amps A1, A2 preferably have their offsetadjustment inputs grounded, as indicated in FIG. 6.

Importantly, first and second op amps A1, A2 have their bias currentsetting inputs grounded via high-resistance resistors R11 , R12. Theoutput of second op amp A2 drives the base of a first transistor Q1 viaa series resistor R13, the base being biased to VCC via a resistor R14.The collector of first transistor Q1 directly drives the base of asecond transistor Q2 and drives the emitter of transistor Q2 via aresistor R15. Transistor Q2's collector is fed back to the base oftransistor Q1 and transistor Q2's emitter is connected via alight-emitting diode (LED) D1 to the input of second op amp A2. Personsskilled in the art will appreciate that second op amp A2, transistorsQ1, Q2 and LED D1 and their closely associated support circuitry form anextremely low-current monostable MULTIVIBRATOR/DRIVER and cause LED D1visibly to blink at a desired frequency and duty cycle determined by thevalues of the surrounding components. COMPARATOR andMULTIVIBRATOR/DRIVER together thus are labelled ANNUNCIATOR in FIG. 6,by which broadly is meant audio, visual or other means of indicating theoperational status of CHARGER and/or EC eyewear 38'.

In one exemplary embodiment of the invention, preferably precisionresistor R6 is 7.5 MΩ and preferably precision resistor R7 is 1.13 MΩ.In such embodiment, resistor R8 is 430 kΩ and capacitor C1 is 0.47 μF.Resistors R9, R11, R12 are 39 MΩ. R10 is 18 MΩ, R13 is 18 kΩ, R14 is 4.7kΩ and R15 is 10 kΩ. Op amps A1, A2 preferably are CA3440Ms andtransistors Q1, Q2 are 2N3904s. Persons skilled in the art willappreciate that, within the spirit and scope of the invention, differentcircuit topologies, devices and component values may be used.

It may be seen then that ANNUNCIATOR provides a preferably visible, butultra-low-current indication to the user of battery charger case 110that proper contact is made between contacts 116, 118 of case 110 andbetween corresponding terminals 106, 108 located in bridge 84 of eyewear38'. LED D1 thus reassures the user that recharging is taking place, andinforms the user when recharging is complete. Yet the unique low-powerCOMPARATOR and MULTIVIBRATOR/DRIVER circuits that collectively formANNUNCIATOR, as described and illustrated by reference to FIG. 6, doesso while drawing, or consuming, current from battery B₁ at a level ofpreferably less than approximately 1 milliampere (mA), more preferablyless than approximately 100 microamperes (μA) and most preferably onlyapproximately 50 microamperes (μA), each of which represents a tinyfraction of the capacity of battery B₁. As a result, battery B₁ isvirtually untaxed by ANNUNCIATOR so that its energy is used insteadsubstantially solely to recharge the lead acid battery pair withineyewear 38'.

It is estimated that ANNUNCIATOR has the capacity visibly, constantly toblink LED D1 for nearly eight years (subject, of course, to the shelflife of battery B₁, which may be only approximately five years).Obviously, with LED D1 blinking typically only when eyewear 38' isproperly situated within case 110 for battery charging or recharging,the effective life of ANNUNCIATOR is practically unlimited, andvirtually all of the capacity of battery B₁ is dedicated to its primarypurpose of recharging.

As illustrated and described herein, external battery, or CHARGERcircuit, produces up to approximately 1.0 mA of charging current at2.2-2.4 V (adjusted by setting potentiometer K1) at contacts 116, 118and is capable of recharging fully depleted lead acid batteries 16, 18of eyewear 38' in less than approximately eight hours and preferablyless than approximately five hours, while producing a visual indicationof when it is charging. It is believed that external battery CHARGERcircuit would fully recharge depleted lead acid battery pairs withineyewear 38', for more than approximately six months of normal use ofeyewear 38' and at normal charging frequency, before replacement ofbattery B₁ were required.

The invention now may be seen to involve an electrochromic eyewearsystem that includes not only 1) electrochromic eyewear 38' describedabove but also 2) an external battery charger, e.g. battery CHARGERcircuit therefor, with the charger having an electro-mechanicalconfiguration for conductive electrical connection for charging theeyewear's one or more batteries and a mechanical connection for grippingthe eyewear's frame during the charging thereof.

As described and illustrated herein, eyewear 38' preferably includes 1a)an eyewear frame such as frame F; 1b) an electrochromic lens such aslens 32 mounted in the frame, with the lens being capable of switchingits visible light transmissivity; 1c) one or more switches such asswitches S1, S2 mounted in the frame, with at least one of the switchesbeing operatively connected to the lens, e.g. as illustrated in FIG. 1;and 1d) a power supply such as power supply 10 contained within theframe, with the power supply including a controller such as controller12, at least one lead acid battery for supplying current to thecontroller and for supplying switching current through the connectedswitch to the lens.

Preferably, an external battery charger, or battery CHARGER circuit,also forms a part of such an EC eyewear system. Such an external chargeris integrally housed in an eyewear enclosure, or case 110, asillustrated in FIG. 5. Also preferably, the external battery charger isbattery operable and thus portable without external connection, forexample, to an AC power source or converter. As described above inaccordance with the preferred embodiment, battery charger, or batteryCHARGER circuit, includes ANNUNCIATOR for communicating to a user whenthe charger is supplying charging current to the rechargeable batteriesof eyewear 38'.

As described and illustrated herein, ANNUNCIATOR preferably is opticaland, accordingly, such communicating is visual. Those of skill in theart of course will appreciate that such communicating with a user via anannunciator instead might be aural, as by an intermittent beeper. Italso might take different visual forms, e.g. it might include a textualor graphic display for showing the status of the eyewear chargingprocess, e.g. via a bar graph.

Importantly, in accordance with the preferred embodiment of theinvention, when battery charger, or battery CHARGER circuit, is batteryoperable, ANNUNCIATOR is operated intermittently, i.e. at apredetermined frequency and duty cycle, thereby to conserve power on theexternal battery-operable battery CHARGER.

While the present invention has been shown and described with referenceto the foregoing preferred embodiment, it will be apparent to thoseskilled in the art that other changes in form and detail may be madetherein without departing from the spirit and scope of the invention asdefined in the appended claims.

We claim:
 1. A lens driver for supplying power to electrochromic eyewearincluding a frame and one or more lenses and lenstransmissivity-switching means, the lens driver comprising:one or morebatteries contained within such frame of the electrochromic eyewear, anda switching power converter operatively coupled with said one or morebatteries, said converter being contained also within such frame, saidconverter including full-bridge configured output transistors providingbidirectional current flow and low voltage drop in either direction, theconverter further including an output filter for producing a smoothoutput voltage waveform to charge the one or more lenses to a determinedvoltage level representing a desired visible light-transmissivity,whereby said lens driver including said one or more batteries coupledwith said switching power converter supplies power to the electrochromiceyewear without external recharging for approximately two thousandcycles of such lens-transmissivity switching means.
 2. The lens driverof claim 1, wherein said one or more batteries include a first batteryof a given cell type and a second battery of a given cell type, andwhere said cell type of said second battery is different from said celltype of said first battery.
 3. The lens driver of claim 2, wherein saidfirst battery includes a lithium-type cell and wherein said secondbattery includes a lead acid-type cell.
 4. The lens driver of claim 2,wherein said first battery includes a cell having a composition that ischosen from lithium thionyl/chloride and lithium carbon monofluoride. 5.The lens driver of claim 2, wherein each of said first and said secondbatteries occupies a volume of less than approximately 1.0 milliliter.6. The lens driver of claim 2, wherein each of said first and saidsecond batteries occupies a volume of less than approximately 0.8milliliter.
 7. The lens driver of claim 2, wherein each of said firstand said second batteries occupies a volume of less than approximately0.65 milliliters.
 8. The lens driver of claim 2, wherein said first andsaid second batteries occupy volumes that are approximately equal to oneanother.
 9. The lens driver of claim 8, wherein the shape of each ofsaid first and said second batteries is elongate and of generallyuniform cross section, with a length-to-width ratio of at leastapproximately 5:1.
 10. The lens driver of claim 8, wherein the shape ofeach of said first and said second batteries is elongate and ofgenerally uniforms cross section, with a length-to-width ratio ofapproximately 7:1.
 11. The lens driver of claim 8, wherein the shape ofeach of said first and said second batteries is elongate and ofgenerally uniform cross section, with a length-to-width ratio of atleast approximately 8:1.
 12. The lens driver of claim 2, wherein thesizes and shapes of said first and said second batteries areapproximately equal.
 13. The lens driver of claim 1, wherein saidswitching power converter occupies a volume of less than approximately0.15 milliliter.
 14. The lens driver of claim 1, wherein said switchingpower converter occupies a volume of less than approximately 0.1milliliter.
 15. The lens driver of claim 1, wherein said switching powerconverter occupies a volume of less than approximately 0.05 milliliter.16. The lens driver of claim 1, further comprising a flex circuitextending along said frame and operatively electrically interconnectingsaid one or more batteries and said switching power converter.